Castor base with load sensor

ABSTRACT

Systems and methods for a load sensing system that determines a mass on a bed. The systems generally are in the form of a castor base, particularly one that can be used as part of an adjustable hospital bed. The load sensing system serves to determine the mass of any object or objects (typically a human or animal patient) which is placed on the bed by having the mass create a force on lever arms of a plurality of load cells in the castor base. The load sensing systems are designed to work without hindering the adjustable functionality of the bed and can accurately determine mass (weight) at any position of the bed, and potentially even while the bed is adjusting between positions.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application is Continuation of U.S. Utility patent application Ser.No. 15/470,437, filed Mar. 27, 2017 and now U.S. Pat. No. 10,555,852,which claims the benefit of U.S. Provisional Patent Application Ser. No.62/314,158, filed Mar. 28, 2016. The entire disclosure of all the abovedocuments is herein incorporated by reference.

BACKGROUND 1. Field of the Invention

This disclosure is related to the field of load sensing in lifts. Inparticular, it is for the positioning of a load sensor in the castorbase of an adjustable hospital bed.

2. Description of the Related Art

Within a hospital, the bed is ubiquitous. It is generally the most majorpiece of furniture in every hospital room and is the one primarilyutilized by the patient. The reasons are clear. Patients in hospitaloften need to be transported by others, and often need to be transportedwhen they are under the effects or anesthesia, asleep, or otherwiseincapacitated.

Hospital beds are, therefore, often required to have much morefunctionality than traditional beds. They generally need to be on wheelsto be easily moveable within the hospital. They also commonly need to beadjustable in a variety of different directions to allow patients thatare unable to move themselves, and often lack even basic motor control,to be moved by others from and to the bed safely and to allow patientsthat may be awake and at least partially mobile to be comfortable inthem both sleeping and performing other activities such as eating.

One element of interest for patients that are in the hospital is theirweight (body mass). This can be relevant to determine the amount ofcertain medications they should be provided with, for other forms oftreatment, and for general monitoring. However, when patients cannotstand or sit, they generally cannot utilize traditional scales whichrequire them to position and hold their body on the sensing mechanism.Therefore, it is desirable to have weight sensing mechanisms which canbe used by a patient that is unconscious and ideally can be used withoutthem having to be moved any additional times. Traditionally, hospitalshave utilized scales which are capable of having a bed or wheelchairrolled onto them for this purpose. However, this means that the patienthas to be transported from the room to the scale and the scales maybecome a chokepoint in hospital procedures if they are needed by a largenumber of patients at the same time. These systems can also introduceerrors if the mass of the bed, wheelchair, and any other ancillaryobjects thereon are not taken into account in the mass calculation. Thiscan result in an inflated weight calculations which in turn may resultin overmedication or other problems.

SUMMARY

Because of these and other problems in the art, described herein aresystems and methods for a castor base, particularly one that can be usedas part of an adjustable hospital bed, that includes a load sensingsystem. The load sensing system serves to determine the mass of anyobject or objects (typically a human or animal patient) which is placedon the bed. The load sensing systems are designed to work withouthindering the adjustable functionality of the bed and can accuratelydetermine mass (weight) at any position of the bed, and potentially evenwhile the bed is adjusting between positions.

There are described herein, among other things, systems and methods fora load sensing system that determines a mass on a bed. The systemsgenerally are in the form of a castor base that serves to determine themass of any object or objects which is placed on the bed by having themass create a force on lever arms of a plurality of load cells in thecastor base.

There is described herein, among other things, an adjustable bedcomprising; a main frame supporting a mattress; a lift connected to saidmain frame and having an axle spaced from said connection to said mainframe; and a castor base rotationally connected to said axle, saidcastor base comprising: two auxiliary beams, each auxiliary beamsupporting at least one castor; a load cell mounted to each of saidauxiliary beams via a main housing and having a lever arm extendingtherefrom; wherein said lever arm is of generally cylindrical shape; andwherein a force applied to said lever arm in a direction generallyperpendicular to a direction said lever arm extends from said mainhousing is detected by said load cell; and a bushing positioned on eachof said lever arms to rotate about said lever arm without rotating saidlever arm it is positioned on; wherein, said axle of said lift isconnected to said bushing so that said axle can rotate relative to saidcastor base without rotating said lever arms; and wherein, placing amass on said main frame creates a force on each said lever arm detectedby said load cell.

In an embodiment, the bed is an adjustable hospital bed.

In an embodiment of the bed, the main frame includes at least one sidepanel;

In an embodiment, the bed further comprises a main beam interconnectingsaid auxiliary beams.

In an embodiment of the bed, the main beam is of generally “L” shapehaving two generally perpendicular arms and said axle rotates withinsaid space defined by said two arms.

In an embodiment of the bed, each of said auxiliary beams includes twocastors each of said two castors being arranged toward an opposing endof said auxiliary beam.

In an embodiment of the bed, wiring from each said load cell extendsinto said axle.

In an embodiment of the bed, each said load cell is electronicallyconnected to a controller which also actuates said lift.

In an embodiment of the bed, the lift is a “Y” lift or a scissor lift.

In an embodiment of the bed, the bushings and said lever arms arepositioned inside said axle.

There is also described herein, in an embodiment, an adjustable bedcomprising: a main frame having a foot portion and a head portion andsupporting a mattress; a foot lift connected to said foot portion andhaving an axle spaced from said connection to said main frame; a headlift connected to said head portion and having an axle spaced from saidconnection to said main frame; a foot castor base rotationally connectedto said axle of said foot lift and a head castor base rotationallyconnected to said axle of said head lift, each of said foot castor baseand said head castor base comprising: two auxiliary beams, eachauxiliary beam supporting at least one castor; a load cell mounted toeach of said auxiliary beams via a main housing and having a lever armextending therefrom; wherein said lever arm is of generally cylindricalshape; and wherein a force applied to said lever arm in a directiongenerally perpendicular to a direction said lever arm extends from saidmain housing is detected by said load cell; and a bushing positioned oneach of said lever arms to rotate about said lever arm without rotatingsaid lever arm it is positioned on; wherein, said axle of said lift isconnected to said bushing so that said axle can rotate relative to saidcastor base without rotating said lever arms; and wherein, placing amass on said main frame creates a force on each said lever arm detectedby said load cell.

In an embodiment of the bed, the foot lift and said head lift areconfigured to move independently of each other.

In an embodiment, the bed further comprises a main beam interconnectingsaid auxiliary beams within each castor base.

In an embodiment of the bed, the main beam is of generally “L” shapehaving two generally perpendicular arms and said axle rotates withinsaid space defined by said two arms.

In an embodiment of the bed, each of said auxiliary beams includes twocastors each of said two castors being arranged toward an opposing endof said auxiliary beam.

In an embodiment of the bed, the bushings and said lever arms on saidfoot castor base are positioned inside said axle attached to said footcastor base and said bushings and said lever arms on said head castorbase are positioned inside said axle attached to said head castor base.

In an embodiment of the bed, wiring from each said load cell extendsinto said axle said lever arm is positioned within.

In an embodiment of the bed, electrical signals indicative of said forceon each of said load cell are combined at a single controller todetermine said mass.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows an embodiment of an adjustable bed including an embodimentof a load sensing castor base.

FIG. 2 shows an embodiment of an adjustable bed including a load sensingcastor base with the protective cover removed so the rotational axle isvisible.

FIG. 3 shows a closer in view of the castor base of the adjustable bedof FIG. 2.

FIG. 4 shows an embodiment of one of the load sensor connections of theadjustable base of FIG. 2. The collar of the bushing and the end of themain housing of the load cell where the lever arm connects are visible.

FIG. 5 shows an alternative angle of FIG. 4.

FIG. 6 shows an exploded view of a portion of an embodiment of a loadsensing castor base showing one of the four load sensors.

FIG. 7 shows a partially transparent view of an embodiment of a loadsensing castor base showing two of the load sensors.

DESCRIPTION OF PREFERRED EMBODIMENT(S)

FIG. 1 provides an embodiment of an adjustable bed (100) according tothe present disclosure which includes an embodiment of a load sensingsystem. This type of bed (100) is exemplary of the types which can useor include a load sensing castor system and while the castor system isnot limited to use in these types of beds (100), it is useful forillustrative purposes. Similar beds are also discussed in U.S. Pat. Nos.8,845,264 and D661,122, the entire disclosures of which are hereinincorporated by reference. Throughout this disclosure it will generallybe discussed that the bed (100) is a bed for use in a hospital or othermedical care facility as that is a common type of bed (100) where a loadsensing system is desirable, but the present disclosure is not limitedto this particular application.

The depicted bed (100) includes a main frame (101) which serves tosupport the mattress, linens, and other non-durable components of thebed as well as, ultimately, the patient. In the depicted embodiment, themain frame (101) is made up of an exterior frame (103), which includesvarious hinges for adjustability, and a plurality of slats (105) whichserve as the primary weight bearing support. The main frame (101) willgenerally comprise two major portions, a foot portion (191) and a headportion (193). The bed (100) may also include a variety of hospitalspecific components such as side panels (111) and (113) to inhibit apatient from falling off the sides, and a head board (115) and footboard(117).

The depicted bed (100) is adjustable so that the foot portion (191),head portion (193), or any combination thereof can be moved upwards ordownward. The adjustment is generally accomplished by a pair of “Y” orscissor lifts (125) one of which is arranged at each of the head portion(193) and foot portion (191) of the bed (100). The depicted lifts (125)each comprise a main raise arm (121) and a secondary raise arm (123)which serve to both adjust the height of the specific portion, and toadjust the relative angle to provide for the flexibility in movement.Adjustment may be controlled by a controller (127) which serves to powerthe various actuators such as, but not limited to, pneumatic orhydraulic cylinders, motors, worm drives, and related devices andcombinations thereof.

To allow the bed to be rolled, the lifts (125) are generallyrotationally attached to two castor bases (131) one at the head portion(193) and one at the foot portion (191) of the bed (100) via an axle(401). In the depicted embodiment, each of the two castor bases (131)includes four castors (133) which contact the floor upon which the bed(100) is placed and allow it to be rolled, but this particular number ofcastors (133) is by no means limiting. Some or all of the castors (133)may be able to be locked into position by actuation of a foot lock(135).

A load sensor (200) is generally located within each side of each castorbase (131) or at the four “corners” of the bed. Thus, there is generallya load sensor (200) at each set of two castors (133) with two on eachside of the bed (100). Various of the load sensors (200) are best seenin FIGS. 6 and 7, but portions are visible in FIGS. 2-5. The output ofthe load sensors (200) will generally be transmitted to a display (137)which may also provide controls for the load system, and possibly othercomponents of the bed (100). In the depicted embodiment, transmittal isvia a wire harness (201).

As shown in FIG. 1, the connection of the lifts (125) to the castor base(131) is generally covered by a guard (139) which serves to covercertain moving components and prevent inadvertent interaction with theconnection between the lift arms (125) and the castor base (131). In thedepictions of FIGS. 2 through 5, the guard (139) has been removed toprovide a better illustration of the internal components.

To provide for structure, the castor base (131) is generally formed of amain beam (303) running the width of the bed (100) and two auxiliarybeams (301) in a generally “I” shape except that the auxiliary beams(301) are not co-planar with the main beam (303) and are generallyperpendicular to the main beam (303). The castors (133) extend generallydownward from the outside points of the “I”. The main beam (303) isgenerally primarily of a planar shape or “L” shape having two generallyperpendicular arms to allow for the axle (401) of the lift (125) torotate in close proximity to the main beam (303) without contact. In the“L” shape depicted, the axle (125) will generally rotate within thespace defined by the arms as best shown in FIG. 3 The main beam (303)also includes two end portions (305) toward both terminal ends of themain beam (303). The end portions (305) are each formed of generallyhollow tubes which are commonly quadrilateral in cross-section and inthe depicted embodiment are square in cross-section. These end portions(305) will serve as the housings for the main housing (511) of the loadcell (501) and are connected to the auxiliary beams (301) by braces(391) in the depicted embodiment of FIGS. 2-5.

As can be best seen in FIG. 6, each load cell (501) comprises twoportions and is generally a strain-gauge load cell of conventional type.Each load cell (501) will commonly be a shear or bending beam type loadcell as known to those of ordinary skill in the art. However, inalternative embodiments, single point cells could be used. The mainhousing (511) of the load cell (501) is of typical design and will serveto house the electronics and other components known to those of ordinaryskill in the art. The lever arm (513) (or bending beam) extends from themain housing (511) and will generally be in the shape of a roundcylinder with its central axis arranged to extend into said main housing(511). It may have a single diameter or multiple diameters along itslength depending on the shape of bushing (523). The lever arm (513) isgenerally connected to the main housing (511) so that force exerted onthe lever arm (513) generally perpendicular to the direction the leverarm (513) extends foam the main housing (511) (generally perpendicularto the axis of the cylinder of the lever arm (513)) can be detected.

As can be best seen in FIGS. 4, 5, and 7, the main housing (511) ispositioned in an end portion (305) of the castor base (131). The leverarm (513) then extends outward and has placed thereon a collared bushing(523). The bushing (523) will generally be rotationally connected to thelever arm (513) and can rotate around the lever arm (513) withouttwisting the lever arm (513). The outside of the main body (525) of thebushing (523) will generally be placed into the hollow interior of theaxle (401) of the lift (125) and rigidly positioned so that the bushing(523) cannot rotate relative to the axle (401). To correctly positionthe bushing (523), the axle (401) will generally be positioned with anend adjacent to the collar (527). This is most clearly shown in FIGS. 4and 5. Wiring (529) each the load cell (501) in the same castor base(131) will commonly extend through the axle (401) to the wiring harness(201) for electrical connection to other components including the wiringfrom the other load cells (501) on the other castor base (131).

As can be best seen in FIGS. 2-5 and 7, each load sensor (200) comprisesan independent load cell (501) which is located to determine the weightapplied at any floor connection. Namely, at each pair of castor wheels(133) at each corner of the bed (100) by attachment to the opposing endsof the main beam (303). Thus, the mass of any object on the bed frame(101), whose weight will be distributed across the bed frame (101), canbe determined from the value of the four sensors (200) regardless of howthe bed (100) is adjusted.

In operation, the load cells (501) are able to measure the mass of anyobject on the bed (100) regardless of the position of the lifts (125)and adjustment of the bed (100). Each load cell (501) will be able todetect the load applied to it by the lift (125) pushing the axle (401)downward. This will then serve to push the lever arm (513) downwardcreating shear or bend between the lever arm (513) and main body (511).That force can be detected by electronics in the main body (511) andconverted into the weight of the object on the bed (100) by comparingthe value across all four sensors (200) which should, between them,support all the weight of the object on the bed (100) (as well ascomponents of the bed (100) above them, but those will generally beknown and zeroed out).

As should be apparent, having the lever arm (513) be cylindrical allowsfor the lever arm (513) to be placed in the bushing (523) which isconnected to the axle (401). As the bushing (523) can rotate about thelever arm (513), the lift (125) can freely adjust, which causes the axle(401) to rotate, while simultaneously not disconnecting or altering howforce is applied to the lever arm (513). Thus, with appropriate controlsoftware or hardware, the sensors (200) can determine the mass of anyobject lying on the bed (100) regardless of the position of the lifts(125) and adjustment of the bed (100).

Throughout this disclosure, relative terms such as “generally,” “about,”and “approximately” may be used, such as, but not necessarily limitedto, with respect to shapes, sizes, dimensions, angles, and distances.One of ordinary skill will understand that, in the context of thisdisclosure, these terms are used to describe a recognizable attempt toconform a device to the qualified term. By way of example and notlimitation, components such as surfaces described as being “generallyparallel” will be recognized by one of ordinary skill in the art to notbe, in a strict geometric sense, parallel, because, in a real worldmanufactured item, no surface is generally ever truly planar. A “plane”is a purely geometric construct that does not actually exist, and nocomponent is truly “planer” in the geometric sense. Thus, no twocomponents of a real item are ever truly “parallel”, as they existoutside of perfect mathematical or geometric representation. Variationsfrom geometric descriptions are inescapable due to, among other things:manufacturing tolerances resulting in shape variations, defects, andimperfections; non-uniform thermal expansion; design and manufacturinglimitations, and natural wear.

There exists for every object a level of magnification at whichgeometric descriptors no longer apply due to the nature of matter. Oneof ordinary skill will understand how to apply relative terms such as“generally,” “about,” and “approximately” to describe a range ofvariations from the literal meaning of the qualified term in view ofthese and other considerations as well as that use of such mathematicalterms is not intended to mean their strict mathematical relationship,but a general approximation of that relationship in the real world.

Further, use in this description of terms such as “forward” and“backward” do not actually require that certain surfaces or objects becloser or further away from a surface at any given time or to denote anecessary arrangement of components or components relative to a user.Instead, they are generally used to denote opposite directions inconjunction with the standard arrangement of the FIGS. provided hereinso as to give relative positioning of elements. Similarly, terms such as“inside” and “outside”, “left” and “right”, and “top” and “bottom” areused to show relative directions or positions as opposed to absolutelocation relative any other component or a human user or observer.

It will further be understood that any of the ranges, values,properties, or characteristics given for any single component of thepresent disclosure can be used interchangeably with any ranges, values,properties, or characteristics given for any of the other components ofthe disclosure, where compatible, to form an embodiment having definedvalues for each of the components, as given herein throughout. Further,ranges provided for a genus or a category can also be applied to specieswithin the genus or members of the category unless otherwise noted.

While the invention has been disclosed in conjunction with a descriptionof certain embodiments, including those that are currently believed tobe the preferred embodiments, the detailed description is intended to beillustrative and should not be understood to limit the scope of thepresent disclosure. As would be understood by one of ordinary skill inthe art, embodiments other than those described in detail herein areencompassed by the present invention. Modifications and variations ofthe described embodiments may be made without departing from the spiritand scope of the invention.

The invention claimed is:
 1. A castor base for detecting load, thecastor base comprising: at least two auxiliary beams, each auxiliarybeam supporting at least one castor; a load cell mounted to each of saidauxiliary beams via a main housing and having a lever arm extendingtherefrom, wherein a force applied to said lever arm in a directiongenerally perpendicular to a direction said lever arm extends from saidmain housing is detected by said load cell; a bushing positioned on eachof said lever arms to rotate about said lever arm without rotating saidlever arm it is positioned on; and an axle connected to said bushing sothat said axle can rotate relative to said castor base without rotatingsaid lever arms.
 2. The base of claim 1 further comprising a main beaminterconnecting said auxiliary beams.
 3. The base of claim 2 whereinsaid main beam is of generally “L” shape having two generallyperpendicular arms and said axle rotates within said space defined bysaid two arms.
 4. The base of claim 1 wherein each of said auxiliarybeams includes two castors, each of said two castors being arrangedtoward an opposing end of said auxiliary beam.
 5. The base of claim 1wherein wiring from each said load cell extends into said axle.
 6. Thebase of claim 1 wherein said bushings and said lever arms are positionedinside said axle.
 7. The base of claim 1 wherein at least one of saidlever arms is of generally cylindrical shape.